I need help understanding this

Question

A line passes through point . A second point on the line has an x-value that is 125% of the x-value of point  and a y-value that is 75% of the y-value of point . Use point  to write an equation of the line in point-slope form.

Answer 1

Point slope form:

y-y₁=m(x-x₁)

x₁ = 1.25x and y₁ = .75y

m = (change in y)/(change in x) = (y-.75y)/(x-1.25x) = .25y/(-.25x) = -y/x

The first sentence has the point blanked out. Once we know the point (x₁,y₁), substitute in the values into

y - y₁ = (-y₁/x₁)(x-x₁)